1. Field of the Invention
The present invention relates to vertical cavity surface emitting lasers.
2. Description of the Related Art
A non-patent document, Electronic Letters, vol. 42, no. 22, pp. 1281 to 1283, 2006, describes a vertical cavity surface emitting laser (VCSEL). This VCSEL includes a distributed Bragg reflector (DBR) disposed on a GaAs substrate. The DBR is constituted by n-type AlGaAs semiconductor layers and n-type GaAs semiconductor layers alternately stacked. These semiconductor layers are doped with an n-type impurity, Si. The DBR constitutes part of a cavity and also serves as a path for carriers to be supplied to an active layer.